As far as i know discrimination is defined quite clearly in the EU. However, it is not discrimination if a company requires the prospective employee to meet certain medical standards that are tighter than the law requires. It might be discrimination if those standards are designed in a way that they make it impossible for a certain gender to meet them.
There was a case of a prospective cadet that passed all of Lufthansas tests and in the end was not allowed into the program because she was 3.5cm too small. She lost the case against lufthansa in the end, although the court agreed with her assessment that the minimum height requirement of Lufthansa (165cm) discriminates women as a much larger percentage of them is below that. Safety was one of the reasons cited by the court.
In the end companies can choose who they hire. They can discriminate based on age within very tight limits, they cannot discriminate based on gender, sexual orientation and religious belief.